Abstract

Introduction: Food allergy (FA) is heterogeneous disease, affecting multiple organs like skin, respiratory or gastrointestinal tracts, which have different forms from a local allergy to a systemic anaphylaxis. The prevalence of FA is about 4% among children in the world and the prevalence is increasing recently. Th2 and IgE-mediated reactions play an important role in this disease. In this study we determined the most common food allergens in children referred to Mofid Children’s Hospital.

Materials and methods: This cross-sectional study was performed on 396 patients with skin, respiratory and gastrointestinal allergies, which were referred to Mofid Children’s Hospital, 2013-15. Allergen specific IgE was measured via an immunoblotting method using AlleisaScreen® system kit and their data were collected.

Results: Of 396 patients 246 (62.1%) were male and 150 (37.9%) were female. The range of patient’s age was between1-12 and the mean± SD were 4.72±2.91 years. The most common allergens were milk, wheat flour, egg white, casein and cheese mix, respectively.

Conclusion: This study showed that the order of common food allergens in this study was different from other reports; this might be due to the different food habits and /or ethnic diversities.

Introduction

According to a definition expressed by the United States National Institutes of Allergy and Infectious Diseases (NIAID)-sponsored guidelines in 2010, food allergy is defined as ‘‘adverse health effect arising from a specific immune response that occurs reproducibly on exposure to a given food [1]. A study was performed by Gupta et al. in 2010, in which the prevalence of food allergy was about 8% [2]. And another study showed that the prevalence of food allergy is between 1-10% of a population [3]. Cow’s milk allergy in children worldwide is about 1.8-7.5% that can reach up to 15-5% [4]. Food allergy may affect different organs including the skin, gastrointestinal or respiratory tracts [5,6]. Sex, race, obesity and an increase in the level of hygiene are considered to be risk factors of allergy. For example allergy affects males more than females and also is more prevalent in African race [7]. Common food allergens are different in different countries; we designed this study to find the most common food allergens among allergic children referring to Mofid Children’s Hospital (2013-2015).

Materials and Methods

This cross-sectional study was performed on 396 patients, which referred to Mofid Children’s Hospital in a three-year period (2013-15) All patients complained from skin, respiratory and gastrointestinal tracts allergy symptoms. Allergen specific IgE was measured via an immunoblotting method using AlleisaScreen® system kit. Test results were reported as 0-6 positive. These data were collected and analyzed via SPSS version 22 software.

Results

Of 396 patients, 245 (61.9%) were male and 150 (38.1%) were female. The range of patient’s age was between 1-12 and the mean± SD were 4.72±2.91 years. Specific IgE more or equal to 2+ was considered to be positive. The most common allergens: cow’s milk, wheat flour, egg white, casein and cheese mix, respectively (Table 1 & Figure 1).

Allergen

N

Percentage

Cow's milk

148

37.3%

Wheat flour

62

15.6%

Egg white

49

12.4%

Casein

40

10.1%

Cheese mix

34

8.6%

Sesame seeds

29

7.3%

Walnut

24

6%

Hazelnut

23

5.8%

Citrus mix

23

5.8%

Peanut

17

4.3%

Carrot

16

4.2%

Potato

16

4.2%

Tomato

14

3.5%

Celery

14

3.5%

Egg yolk

8

2.1%

Banana

6

1.6%

Almond

6

1.6%

Strawberry

4

1%

Soy beans

4

1%

Fish mix

4

1%

Shrimps

3

0.8%

Cocoa

0

0%

Table 1:The numbers of positive specific IgE to different food allergens in total population of patients.

Figure 1: The most common food allergens among all patients.

The numbers of patients between 1-2.99 years were 122 patients, among whom, 80 patients (65.6%) were male, and 42 (34.4%) were female. The most important allergen substances among children with allergies in this group were: cow's milk, wheat flour, walnuts, sesame and casein, respectively (Table 2 & Figure 2).

Allergen

N

Percentage

Cow's milk

38

31.1%

Wheat flour

16

13%

Walnut

13

10.6%

Sesame seeds

13

10.6%

Casein

12

9.8%

Egg white

8

6.6%

Cheese mix

6

4.9%

Hazelnut

6

4.9%

Citrus mix

4

3.3%

Almond

4

3.3%

Potato

3

2.4%

Peanut

3

2.4%

Carrot

2

1.6%

Egg yolk

1

0.8%

Tomato

1

0.8%

Celery

1

0.8%

Banana

1

0.8%

Strawberry

1

0.8%

Soy beans

1

0.8%

Cocoa

0

0%

Fish mix

0

0%

Shrimps

0

0%

Table 2: The numbers of positive specific IgE to different food allergens among patients in range of 1 -2.99 years.

Figure 2: The most common food allergens among patients in range of 1-2.99 years old.

The number of children with an age range from 3 to 5.99 years were 174, among which, 104 (59.8%) were male, and 70 patients (40.2%) were female. The most allergens among children with allergies were cow's milk, egg white, wheat flour, casein and cheese mix, respectively (Table 3 & Figure 3).

Allergen

N

Percentage

Cow's milk

75

42.1%

Egg white

30

16.9%

Wheat flour

29

16.3%

Casein

20

11.3%

Cheese mix

20

11.3%

Sesame seeds

9

5%

Citrus mix

9

4.7%

Peanut

9

5.1%

Hazelnut

9

5.1%

Walnut

6

3.4%

Celery

6

3.4%

Potato

6

3.4%

Banana

5

2.8%

Egg yolk

5

2.8%

Carrot

4

2.3%

Tomato

4

2.3%

Fish mix

3

1.7%

Strawberry

2

1.1%

Almond

2

1.1%

Soy beans

2

1.1%

Shrimps

1

0.6%

Cocoa

0

0%

Table 3: The numbers of positive specific IgE to different food allergens among patients in range of 3 -5.99 years.

Figure 3: The most common food allergens among patients in range of 3-5.99 years old.

The number of children with age range of 6-8.99 years were 46 patients, of which, 30 (65.2%) were male, and 16 patients (34.8%) were female. The most common allergens were milk, wheat flour, egg white and hazelnut, respectively (Table 4 & Figure 4).

Allergen

N

Percentage

Cow's milk

19

41.3%

Wheat flour

10

21.8%

Egg white

6

13%

Hazelnut

4

8.7%

Casein

3

6.5%

Cheese mix

3

6.5%

Carrot

3

6.5%

Potato

3

6.5%

Citrus mix

3

6.5%

Peanut

3

6.5%

Tomato

3

6.5%

Walnut

3

6.5%

Shrimps

2

4.4%

Sesame seeds

2

4.4%

Celery

2

4.4%

Egg yolk

1

2.2%

Soy beans

1

2.2%

Cocoa

0

0%

Strawberry

0

0%

Fish mix

0

0%

Banana

0

0%

Almond

0

0%

Table 4: The numbers of positive specific IgE to different food allergens in age range of 6-8.99 years.

Figure 4: The most common food allergens among patients in range of 6 -8.99 years.

The number of children with an age range of 9-12 were 54 of whom, 35 (64.8%) were male, and 19 patients (35.2%) were female. The most common food allergens in this range were cow's milk, carrots, citrus mix, wheat flour, casein and cheese mix, respectively (Table 5 & Figure 5).

Allergen

N

Percentage

Cow's milk

18

33.4%

Carrot

8

14.9%

Wheat flour

7

13%

Citrus mix

7

13%

Casein

6

11.1%

Cheese mix

6

11.1

Egg white

5

9.3%

Tomato

5

9.3%

Celery

5

9.3%

Sesame seeds

5

9.3%

Potato

4

7.4%

Hazelnut

4

7.4%

Fish mix

2

3.8%

Peanut

2

3.7%

Walnut

2

3.7%

Shrimps

2

3.8%

Egg yolk

1

1.9%

Strawberry

1

1.9%

Cocoa

0

0%

Banana

0

0%

Almond

0

0%

Soy beans

0

0%

Table 5: The numbers of positive specific IgE to different food allergens among children 12-9 years.

Figure 5: The most common food allergens among patients in range of 9-12 years.

Discussion

In this study, food allergy to 22 different food allergens were examined ,among which in total population, cow’s milk, wheat flour, egg white, casein and cheese mix, were identified as the most common food allergens, respectively. Similar to previous studies, our results showed that the prevalence of food allergy is higher in males than females [8].

After cow’s milk, wheat flour was identified as the second common food allergen, allergy to wheat flour increases with age until the age of 9.

Nuts such as peanuts and hazelnuts are also considered to be important allergens. About 1% of American population show reaction to peanuts [9]. Although peanuts is the most common allergen among nuts in most regions of the world, according to the results of this study, in Iranian children hazelnut is the most common allergen nuts and walnut was an important food allergen in children 1-3 years old, which considered to be in the third level after cow’s milk and wheat flour, which may because of high consumption of this food stuff and also consumption of this nuts at early ages. Consistent with previous studies, tomato is an important food allergen in Iranian children, which could be due to increased use of this vegetable in the diet of these children [9] (Tables 4 & 5).

In conclusion, according to this fact that some food allergens in Iranian children are different from those in the world, it is crucial to design further population-based studies with larger sample sizes in different regions of Iran [10]. Also proper education and consumption of food stuffs at the proper ages should be considered. Also, in order to define it could be interesting to test people from other nationalities living in Iran and other Iranians who live in other countries.